Virtual Field Trips

Hello everybody,
Here in NSW, there's talk of budget cuts, and whenever that happens, schools look for ways to get rid of what some might consider luxuries - like excursions and field trips.
With that in mind, I was wondering if anybody had any really interesting 'virtual field trip' resources out there. To get the ball rolling, here are a few of my favourites:
Google Lit Trips: http://www.googlelittrips.org/
An Interactive Autopsy (not for the faint-hearted): http://australianmuseum.net.au/interactive-tools/autopsy/
What other ones are out there?